Manufacturing method of oled display and apparatus for manufacturing the oled display

ABSTRACT

A manufacturing method of an active matrix organic light emitting diode (AMOLED) display and an apparatus for manufacturing the AMOLED display, where the display has improved surface flatness and thickness uniformity as well as an improved image quality at edge regions of a pattern. According to the exemplary embodiment of the present invention, an anode electrode is formed on a lower structure of a substrate, an organic layer is formed on the anode electrode by imaging a complex laser beam on a donor film disposed on the substrate having light emitting materials, the complex laser beam having energy distribution inclination over 2%/μm at a threshold energy. The donor film is removed, and a cathode electrode is formed on the organic layer.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a divisional of U.S. patent application Ser. No.11/211,706, filed Aug. 26, 2005, which is a continuation-in-part of U.S.patent application Ser. No. 11/145,936, filed on Jun. 7, 2005, now U.S.Pat. No. 7,563,477, which is a continuation of U.S. patent applicationSer. No. 09/935,332, filed on Aug. 23, 2001, now U.S. Pat. No.6,936,300, and claims the benefit of Korean Application No. 2000-49287filed in the Korean Intellectual Property Office on Aug. 24, 2000, thedisclosures of which are incorporated herein by reference.

BACKGROUND OF THE INVENTION

1. Field of the Invention

An aspect of the present invention relates to a manufacturing method ofan active matrix organic light emitting diode (AMOLED) display and anapparatus for manufacturing the active matrix organic light emittingdiode (AMOLED) display. More particularly, an aspect of the presentinvention relates to a method for fabricating an organic light emittingdiode (OLED) display having improved surface flatness and thicknessuniformity as well as an improved image quality at edge regions of apattern.

2. Description of the Related Art

An OLED display is a display device that electrically excitesfluorescent organic material for emitting light and forms an image bycontrolling a voltage or current of N×M numbers of organic lightemitting cells.

Each of the light emitting cells include an anode electrode which is ahole injection electrode, an organic layer having an light emittinglayer (EML), and a cathode electrode which is an electron injectionelectrode. Excitons are formed by combining holes and electronsimplanted into an organic layer from the respective electrode, and animage is displayed when the excitons are reduced from an excited stateto a ground state.

Generally, the organic layer is formed by a multi-layer structureincluding an electron transport layer (ETL), a light emitting layer andhole transport layer (HTL), and the multi-layer structure may furtherincludes an electron injection layer (EIL) and a hole injection layer(HIL).

In the OLED display having the above described organic light emittingcells, the organic layer is designed to create three colors (i.e., red(R), green (G), and blue (B)).

In addition, the organic layer is generally formed by a vacuumevaporative deposition process using a shadow mask or by a conventionaloptical etching process.

However, the vacuum evaporative deposition process has limitationsreducing the physical gap between the patterns, and it is difficult toform a minute pattern to a level of tens of μm's which is required toprevent the possible deformation of the mask.

When the optical etching process is applied, although it is possible toform the minute pattern, practical application becomes difficult sincethe property of the light emitting material forming the light emittinglayer may be deteriorated by the developing solution or the etchingsolution.

Therefore, a thermal transferring method has been recently proposed toform the light emitting layer.

The thermal transferring method converts light emitted from a lightsource into thermal energy by which an image formation material istransferred to a substrate to form a color pattern. Therefore, toperform the thermal transferring method, a light source, a donor filmand a substrate are required.

Relating to the thermal transferring method, U.S. Pat. No. 5,521,035discloses a method for manufacturing a color filter for a liquid crystaldisplay by a laser thermal transferring method.

In this patent, the color filter is manufactured by a laser inductionthermal transferring method for transferring a color material from adonor film to a substrate such as a glass or a polymeric film. As alaser unit, an Nd:YAG laser system is used for transferring the colormaterial to the surface of the substrate.

As shown in FIG. 1, the Nd:YAG laser forms a Gaussian beam B1 having anenergy distribution of a Gaussian function. When a diameter of theGaussian beam B1 is set large (approximately, above 60 μm), theinclination of the energy distribution is smoothly reduced as it goesaway from the center point O.

Therefore, as shown in FIG. 2, when the light emitting layer is formedby imaging the Gaussian beam B1 having a predetermined diameter to adonor film 100 in an X-direction, the image quality at the lightemitting layer corresponding to an edge region 110 of the donor film 100is deteriorated compared to a central portion along a Y-direction.

When the energy of the laser beam is intensified to improve the imagequality at the edges in order to solve the above problem, although theimage quality at the edges may be enhanced, the surface of the imagepattern becomes irregular since the energy is excessively increased atthe central portion.

In addition, when the laser thermal transferring method is used, thelight emitting layer needs to be more carefully formed compared to thecolor filter.

That is, in a case of the color filter, color materials beingtransferred to a substrate using the laser thermal transferring methodare formed by distributing pigments for color change into a binderpolymer (e.g., acrylic resin or epoxy resin), and at this time, a rateof concentration of the pigments is from 20 to 40%.

However, the binder polymer is simply pervious to light. Accordingly,types of binder polymer vary in order to form an appropriate colorpattern, and color materials for forming an appropriate pattern may beformed by changing a molecular weight or a glass transition temperature(Tg) value. In general, the color materials have a 60 to 120° Tg valueand a 1,500 to 5,000 molecular weight, and a color layer of the colorfilter formed by the color materials has approximately 1 to 2 μmthickness.

However, slight changes to the properties of the light-emitting material(e.g., Tg value and molecular weight) highly affect the quality of theOLED display.

Accordingly, it is preferable, but not necessary, to adjust the patternquality by adjusting the laser transfer characteristics rather than bymodifying the properties of the light-emitting material since a limit ofpattern quality is controlled by the laser transferring conditions.

In addition, since the light emitting materials used in the OLED displayhave a molecular weight of approximately 10,000 to 100,000 and a Tgvalue of over 100°, a process for forming the organic layer using thelight emitting materials is more difficult than a process for formingthe color layer by using the color materials.

A desired thickness of the organic layer formed by the laser thermaltransferring method is about 50 to 100 nm, which is thinner than thethickness of the color filter.

Accordingly, when the formed organic layer is thinner than the colorlayer, the laser beam transferring condition and energy distribution aremore carefully controlled compared to when the formed organic is thickerthan the color filter.

The above information disclosed in this Background section is only forenhancement of understanding of the background of the invention andtherefore it may contain information that does not form part of theprior art already known in this country to a person of ordinary skill inthe art.

SUMMARY OF THE INVENTION

According to an aspect of the present invention, there is provides amethod for manufacturing an organic light emitting diode (OLED) displayhaving improved surface flatness and thickness as well as improved imagequality at edge regions of a pattern

According to another aspect of the present invention, there is provideda manufacturing method of an OLED display, including, forming an organiclayer on the anode electrode by imaging a complex laser beam on a donorfilm disposed on the substrate having light emitting materials, whereinthe complex laser beam has energy distribution inclination over 2%/μm ata threshold energy.

According to another aspect of the present invention, the complex laserbeam is formed by a composition of more than two laser beams havingdifferent inclinations of energy distribution at the threshold energy.For example, the complex laser beam may be formed of a laser beam havinga 40 to 200 μm diameter in a direction vertical to a scan direction andenergy distribution inclination over 1.0%/μm at the threshold energy anda laser beam having a 30 to 75 μm diameter in the direction vertical tothe scan direction and energy distribution inclination over 3.0%/μm atthe threshold energy.

Additional aspects and/or advantages of the invention will be set forthin part in the description which follows and, in part, will be obviousfrom the description, or may be learned by practice of the invention.

BRIEF DESCRIPTION OF THE DRAWINGS

These and/or other aspects and advantages of the invention will becomeapparent and more readily appreciated from the following description ofthe embodiments, taken in conjunction with the accompanying drawings ofwhich:

FIG. 1 shows a graph representing energy distribution of a laser beamused in a conventional thermal transferring method.

FIG. 2 shows a schematic diagram describing a pattern formation methodin a conventional thermal transferring method.

FIG. 3 shows schematic diagram of an OLED display having an organiclayer formed in a thermal transferring method according to an exemplaryembodiment of the present invention.

FIG. 4 shows a schematic diagram of a configuration of the organic layershown in FIG. 3

FIG. 5 shows a block diagram representing a manufacturing method of anOLED display according to an exemplary embodiment of the presentinvention.

FIG. 6 shows a graph of cross sectional energy distribution of a laserbeam used in the thermal transferring method of FIG. 3.

FIG. 7 shows a schematic diagram of a transferring device used in thethermal transferring method using the laser beam shown in FIG. 6.

DETAILED DESCRIPTION OF THE EMBODIMENTS

Reference will now be made in detail to the present embodiments of thepresent invention, examples of which are illustrated in the accompanyingdrawings, wherein like reference numerals refer to the like elementsthroughout. The embodiments are described below in order to explain thepresent invention by referring to the figures.

FIG. 3 shows schematic diagram of an OLED display having an organiclayer formed in a thermal transferring method according to an exemplaryembodiment of the present invention, FIG. 4 shows a schematic diagram ofa configuration of the organic layer shown in FIG. 3, and FIG. 5 shows ablock diagram representing a manufacturing method of an OLED displayaccording to an exemplary embodiment of the present invention.

As shown in FIG. 3, a buffer layer 12 is formed on a substrate 10, apolysilicon 14 is formed on a part of the buffer layer 12, and a gateinsulating layer 16 is formed on the polysilicon 14 and buffer layer 12.

A transparent glass substrate or opaque resin substrate may be used forthe substrate 10.

A gate electrode 18 is formed on the gate insulating layer 16, aninterlayer insulating layer 20 is formed on the gate electrode 18 andgate insulating layer 16, and a source/drain electrode 22 is formed onthe interlayer insulating layer 20.

The source/drain electrode 22 is electrically connected to the gateelectrode 18 through a contact hole of the interlayer insulating layer20.

A passivation layer 24 is formed on the source/drain electrode 22 andinterlayer insulating layer 20, and an anode electrode 26 is formed onthe passivation layer 24.

The anode electrode 26 is electrically connected to the source/drainelectrode 22 through a contact hole of the passivation layer 24.

As described above, after the anode electrode 26 is formed on a lowerstructure of the substrate 10, an organic layer 28 and cathode electrode30 is formed on the anode electrode 26, and a pixel dielectric layer 32is formed between the passivation layer 24 and the organic layer 28.

The lower structure includes elements 12 to 22 formed on the passivationlayer 24 and under the passivation layer 24.

The organic layer 28 is formed so as to create one color of R, G and B,and may be formed by a multi-layer structure including a hole injectionlayer 28 a, a hole transport layer 28 b, a light emitting layer 28 c,and an electron transport layer 28 d.

While not illustrated, the electron injection layer (EIL) may be formedbetween the electron transport layer 28 d and a cathode layer 30.

Generally, the hole injection layer 28 a, and the hole transport layer28 b are formed between the light emitting layer 28 c and the anodeelectrode 26, and the electron transport layer 28 d is formed betweenthe light emitting layer 28 c and the cathode electrode 30.

The hole injection layer 28 a and hole transport layer 28 b are used forappropriately transferring and implanting the holes and for stablyforming an interface on a surface of an inorganic anode electrode 26.

Aromatic amine compounds called as arylamine may be used for the holeinjection layer 28 a and hole transport layer 28 b.

In further detail, one material selected from the group consisting ofCuPC (Copper phthalocyanine), mTDATA(4,4′,4″-Tris(N-3-methylphenyl-N-phenyl-amino)-triphenylamine), TDAPB(1,3,5-tris(N,N′-bis(4-methoxyphenyl)-aminophenyl)benzene)triphenylamine),1-NaphDATA (4,4′,4″-tris-[N-(1-naphtyl)-N-phenylamino]-triphenylamine),and TPTE (triphenylamine tetramer) may be used for forming the holeinjection layer 28 a, and one material selected from the groupconsisting of TPD(N,N′-diphenyl-N,N′-bis(3-methylphenyl)-1,1′-diphenyl-4,4′-diamine), NPB(N,N′-diphenyl-N,N′-bis(1-naphthyl)-(1,1′-biphenyl)-4,4′-diamine), andSpiro-TPD (2,2,7,7-tetra-(3-methyldiphenylamino)-9,9′-spirobifluorene)may be used for forming the hole transport layer 28 b.

In addition, organic compounds having electron acceptors or organometallic compounds easily accepting electrons may be used for formingthe electron transport layer 28 d.

In further detail, heterocyclic aromatic amine compounds containing anamine group may be used for the organic compounds, and Alq3(tris(8-hydroxyquinolinato)aluminum) and derivatives of Alq3 may be usedfor the organic metal compounds.

Fluorescent or phosphorescent materials may be used for the lightemitting layer 28 c.

In further detail, among the fluorescent materials, one materialselected from the group consisting of Alq3(tris(8-hydroxyquinoline)-aluminum), 4-MAlq3(tris(4-methyl-(8-hydroxyquinoline)-aluminum)), and C545T(10-(2-Benzothiazolyl)-2,3,6,7-tetrahydro-1,1,7,7,-tetramethyl), may beused for green, one material selected from the group consisting of DPVBi(diphenylvinylenebiphenylene), Spiro-DPVBi (spiro-(4,4-bis(2,2 diphenylvinyl)-1,1-biphenyl)), Spiro-6P(2,2′,7,7′-tetrakis(biphenyl-4-yl)-9,9′-spirobifluorene(spiro-sexiphenyl)),BAlq (4-biphenyloxolatoaluminum(III)bis(2-methyl-8-quinolinato)-4-phenylphenolate), and LiPBO(2-(2-hydroxyphenyl)benzoxazolato lithium) may be used for blue, and onematerial selected from the group consisting of DCM(4-(Dicyanomethylene)-2-methyl-6-(p-dimethylaminostyryl)-4H-pyran), andDCTJB(4-(dicyanomethylene)-2-t-butyl-6-(1,1′,7,7′-tetramethyljulolidyl-9-enyl)-4H-pyran)may be used for red.

In addition, one material selected from the group consisting of Alq3(tris(8-hydroxyquinoline)-aluminum), 4-MAlq3(tris(4-methyl-(8-hydroxyquinoline)-aluminum)), CBP(4,4′-N,N′-dicarbazol-biphenyl), BAlq (4-biphenyloxolatoaluminum(III)bis(2-methyl-8-quinolinato)-4-phenylphenolate), BCP(bathocuproine), TCTA (4,4′,4″-Tris(carbazol-9-yl)-triphenylamine), CDBP(4,4′-N,N′-dicarbazol-2,2′-dimethylbiphenyl), andmCP(N,N′-dicarbazolyl-3,5-benzene) may be used for phosphorescent hostmaterials.

One material selected from the group consisting of PtOEP(2,3,7,8,12,13,17,18-octaethyl-12H,23H-porphyrine platinum(II)),Ir(ppy)₃ (fac-tris(2-phenylpyridine)iridium), BtpIr(bis(2-(2′-benzo[4,5-a]thienyl)-pyridinato-N,C3′)iridium(acetyl-acetonate)), Btp₂Ir(acac)(bis(2-(2-benzo[4,5-a]thienyl)pyridinato-N,C2)iridium(acetylacetonate)),Q3Ir (tris(diphenylquinoxalinato)iridium), and Flrpic(iridium(III)bis[(4,6-di-fluorophenyl)-pyridinato-N,C2′]picolinate) maybe used for phosphorescent dopant materials.

According to the exemplary embodiment of the present invention, acomplex laser beam B2 shown in FIG. 6 is used when the organic layer 28is formed.

The complex laser beam B2 is formed by more than two laser beams havingdifferent inclinations of energy distribution at threshold energy.

The complex laser beam B2 is formed by a laser beam B3 having gentleinclination of energy distribution at threshold energy Pe′/2 and laserbeams B4 and B4′ having steep inclination of energy distribution atthreshold energy Pe′/2.

Here, a laser beam having a diameter ranging from 40 to 200 μm in adirection perpendicular to a scan direction and 1.0 to 6%/μm energydistribution inclination at the threshold energy Pe′/2 (e.g., Gaussianbeam) may be used for the laser beam B3.

A Gaussian beam having 1.6%/μm energy distribution inclination at thethreshold energy Pe′/2 is used for the laser beam B3 in the exemplaryembodiment of the present invention.

In addition, a laser beam having a diameter ranging from 30 to 75 um inthe direction perpendicular to the scan direction and energydistribution inclination ranging from 3 to 8%/um at the threshold energyPe″/2 is used for the laser beams B4 and B4′.

Accordingly, forming the complex laser beam B2 by the composition of thelaser beam B3 and the laser beams B4 and B4′, the energy distributioninclination of the laser beam B2 at the threshold energy (Pe/2) reachesover 2.0%/μm which is greater than 1.6%/μm energy distributioninclination of the laser beam B3 at the threshold energy.

FIG. 5 shows a block diagram representing a manufacturing method of anOLED display according to an embodiment of the present invention. Asnoted in operation 51, an anode electrode layer is initially formed.Thereafter, at operation 52, an organic layer is formed by a complexlaser beam having an inclination above 2%/μm at a Pe/2. At operation 53,a donor film is removed and a cathode electrode layer is formed atoperation 54.

In the graph of in FIG. 6, the X-axis denotes a beam diameter in μm, andthe Y-axis denotes beam power W.

Pe denotes a maximum beam power of the laser beam B2 (i.e, a peakvalue), Pe′ denotes a peak value of the laser beam B3, and Pe″ denotes apeak value of the laser beam B4 and B4′.

In addition, the energy distribution inclination shows a variation rate% of beam power according to the variation amount in μm of the beamdiameter, and the variation rate % of the beam power shows the variationamount of beam power with a percentage by setting peak values of therespective laser beams to 100.

The complex laser beam B2 is formed in an anisotropic beam shape of ascan direction (X-direction in FIG. 2) and a direction (Y-direction inFIG. 2) perpendicular to the scan direction, and the complex laser beamB2 has different beam diameters from each other.

For example, the complex laser beam B2 may be formed in an oval shape ora diamond shape having a long axis in the scan direction.

Scan speed varies depending on light emitting materials, and speed from5 to 11 m/sec may be used when a complex laser beam having 8W beam poweris used.

The beam power at a central region is similar with the beam power at anedge region since the energy distribution inclination of the complexlaser beam B2 of the above configuration is great at the thresholdenergy Pe/2.

Accordingly, since a thermal transfer is performed at an edge region ofthe organic layer 28 when the organic layer 28 is formed by transferringthe donor film including light emitting materials by the complex laserbeam B2, the surface roughness of the organic layer 28 may be prevented.

That is, the exemplary embodiment of the present invention preventsunevenness of the organic layer 28 caused when the beam power isincreased to prevent pattern error at the edge region.

FIG. 7 shows a schematic diagram of a transferring device used in thethermal transferring method of FIG. 6.

As shown in FIG. 7, a high output complex laser beam B2 is emitted froma laser source 40 which is a light source.

A high output solid laser using Nd/YAG or a gas laser using CO2 is usedfor the light source.

The complex laser beam B2 is scanned to a donor film 100 through anattenuator 42, a first expander 44, an acousto-optic modulator 46, asecond expander 48, a Y-galvanometer 50, a third expander 52, anX-galvanometer 54, and scan lens 56.

The donor film 100 includes light emitting materials (e.g., fluorescentor phosphorescent materials), and the substrate 10 is formed on a stage58.

Accordingly, the organic layer 28 is formed by transferring the lightemitting materials in an area where the complex laser beam B2 is scannedonto the substrate 10, resulting in the organic layer 28 having highquality surface flatness and thickness uniformity of a pattern.

According to the exemplary embodiment of the present invention, thecathode electrode is formed on the organic layer after forming the anodeelectrode and pixel dielectric layer on the lower structure provided onthe substrate and forming the organic layer using the complex laser beamhaving energy distribution inclination over 2%/μm at the thresholdenergy.

Accordingly, an OLED display having a high quality organic layer may befabricated since an image quality at edge regions of the emitting layermay be improved and the flatness of the pattern surface is enhanced.

While this invention has been described in connection with what ispresently considered to be practical exemplary embodiments, it is to beunderstood that the invention is not limited to the disclosedembodiments, but, on the contrary, is intended to cover variousmodifications and equivalent arrangements included within the spirit andscope of the appended claims.

Although a few embodiments of the present invention have been shown anddescribed, it would be appreciated by those skilled in the art thatchanges may be made in this embodiment without departing from theprinciples and spirit of the invention, the scope of which is defined inthe claims and their equivalents.

1. An apparatus for manufacturing a display, the apparatus comprising: alight source emitting a complex laser beam; an attenuator directing thecomplex laser beam to a donor film disposed on a substrate; a scan lensscanning the complex laser beam over the donor film, the donor filmtransferring light emitting materials to the substrate forming thedisplay; and a stage supporting the donor film and the substrate,wherein the complex laser beam is formed of more than two laser beamshaving different inclinations of energy distribution at a thresholdenergy.
 2. The apparatus of claim 1, wherein the complex laser beam is ahigh output solid laser using Nd/YAG.
 3. The apparatus of claim 1,wherein the complex laser beam is a gas laser using CO₂.